Purpose -Service networks are inherently complex as they comprise of many interrelated actors, often driven by divergent interests. This can result in imbalance, which refers to a situation where the interests of at least one actor in a network are not secured. Drawing on the "balanced centricity" perspective, this paper explores the causes of imbalance in complex service networks.Design/methodology/approach -Adopting a qualitative case-based approach, this paper examines a public health service network that experienced imbalance that was detrimental to the lives of its users: the Mid-Staffordshire NHS Trust, UK. Drawing on service-dominant logic and stakeholder theory, case evidence provides insight into the origin and drivers of imbalance in complex public service networks.Findings -The origin of imbalance stems from competing institutional logics of various actors (patients/public, employees, managers, regulatory bodies, etc.), but the degree to which these competing institutional logics lead to imbalance is moderated by accountability, communication, engagement, and responsiveness within the service network.Research limitations/implications -By uncovering causes of imbalance in complex public service networks, this paper pinpoints important research avenues for developing the balanced centricity perspective.Practical implications -The inherent existence of multiple parallel institutional arrangements makes networks imbalanced, but value creation can be achieved when the appropriate mechanisms are fostered to manage balance between divergent logics. Originality/value -By examining imbalance as the underlying cause of network dysfunction, this research contributes to understanding of the dynamics in, and performance of, complex public service networks.